The phosphor bronzes are copper base alloys containing phosphorus and tin. In this alloysystem, alloys with phosphorus levels in excess of 0.05% and tin levels in excess of 4% are most frequently used. These alloys are known for their poor hot workability, and typically exhibit pronounced cracking during hot rolling at moderately elevated temperatures. This severity of this hot cracking increases with the addition of increased amounts of phosphorus and tin with the result that it is economically impractical to hot roll these alloys at normal commercial hot rolling temperatures.
The foregoing problem was approached in U.S. Pat. No. 3,923,558, to Shapiro et al., commonly assigned. In the patent, certain combinations of iron, and/or cobalt and chromium were provided in a copper-tin-phosphorus alloy for the purpose of maintaining a refined grain size which contributed to improved processability. Improvement was in part achieved by the tendency of iron, cobalt and chromium to form phosphides to prevent the segregation of phosphorus into concentrated areas comprising low melting phases. Though improved processability was achieved in accordance with the Shapiro et al. patent, this improvement was not as consistent as is desirable in a commercial application.